Although Wimbledon 2012 has been the site of some major upsets during the past couple of days, many of the top superstars in the world of tennis are still vying for the title.

Of course, Rafael Nadal is not included in that list of players after his second-round loss to Lukas Rosol. The same goes for Maria Sharapova, after her loss in the fourth round yesterday to Sabine Lisicki.

Big upsets and rain delays have been the talk of Wimbledon thus far, but many of the top tennis players in the world are still left in the draw. Most of them will be likely advancing into the final rounds of the tournament, which will make it that much more exciting.

No matter what, tennis at Wimbledon is always something to look forward to, and with the final rounds approaching fast, it will only get better–no matter whether the top players are around or not.

With the fourth round finally going to finish up this morning–after a rain delayed seventh day yesterday–lets take a look at some of the big names who are still left in the draw and lucky enough to be moving into the quarterfinals.

Roger Federer

With a win in the fourth round against the Belgian Xavier Malisse, Roger Federer will now get a much needed two-night rest before he goes on to play in his quarterfinal match.

Up next for the six-time Wimbledon champion is Russian player Mikhail Youzhny.

Before that match gets going, Federer will be looking to take care of a back injury he was apparently battling during the match against Malisse.

Although he was able to come through in the end with an easy four-set victory, it did not come without a cost. The eventual score finished at 7-6 (7-1), 6-1, 4-6, 6-3 for Federer.

Even though Federer had to talk to his trainer and receive treatment for his ailing back at one point in the match, he is not too worried about it moving forward–he told Mike Dickson of The Daily Mail.

"I felt it going at the start of the first set. I guess it must be a mix of the five-setter in the last round, the two days off and the cold wind today. I'm honestly not too concerned, I've had bad backs over the years, they go as quickly as they come. Of course I have to keep an eye on it but two good nights' sleep and I'll be 100 percent on Wednesday."

With a little rest and treatment, there should be no reason to be concerned about Federer's back in his upcoming match against Youzhny. It should still be an expected win for him, resulting in a semifinal match up against Novak Djokovic.

Novak Djokovic

Playing against his friend–and fellow countryman–Viktor Troicki in the fourth round, Novak Djokovic was able to put all that aside and make sure he kept his focus going into the quarterfinals.

He was able to close out the match in straight sets winning 6-3, 6-1, 6-3.

Djokvic told Helen Gilbert of wimbledon.com just how hard it is to play someone you are really close too.

"It's hard to kind of express the emotions, you know, to celebrate or to be angry. Really it's kind of difficult what to do and how to behave on the court when you're playing one of your best friends. We won Davis Cup together. We are very good friends in the private life."

Even so, Djokovic was able to put the friendship aside during the tournament, and he looks to win Wimbledon for a second consecutive time.

He seems to have his game on track to be able to accomplish that goal. His finals will most likely come two rounds from now when he takes on Roger Federer in the quarters. That being the case because Rafael Nadal has been eliminated from the other side of the draw.

Nonetheless, Djokovic also told Gilbert where his game is, after his last match.

"I returned really well; I served great. The baseline game, I was patient and waiting for a chance to be aggressive. Everything was quite compact, and I'm satisfied."

Djokovic's quarterfinal opponent will be the eventual winner of the delayed match between Richard Gasquet and Florian Mayer.

Agnieszka Radwanska

Radwanska has a lot at stake in her remaining matches at Wimbledon. The third-ranked player in the world has a chance to become No.1, after the early departure of Maria Sharapova in the fourth round.

A win will also mean her first ever Grand Slam title. The closest she has ever come is making it to the quarterfinals, which she has done twice in the past at Wimbledon.

With her side of the draw now considerably weaker, she should be expecting, at the very least, a run to the finals. Once there, anything can always happen.

First off, however, she has to play Maria Kirilenko in the quarterfinals.

Radwanska will be going into this match in good form after a straight set victory against young up-and-coming player Camila Giorgi. The match finished 6-2, 6-3, but Radwanska had very kind words for the young Italian–reported Benjamin Snyder of wimbledon.com.

''I must say that she was really playing good and she's a very good player. I think she can really play good tennis and should be at the top."

It is Radwanska's side of the draw to lose, and if she can play tennis as expected then she should find herself in the finals with a chance to win Wimbledon.

Victoria Azarenka

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With Maria Sharapova's earlier than expected loss, Azarenka is quickly catapulted to being the favorite to win Wimbledon this year.

That's not to say that she will have a clean, easy path to the title, but her biggest opponent is now out of the way. She can expect to play someone who is not nearly as good as Sharapova in the finals, should she still be able to make it there herself.

In her fourth-round match against Ana Ivanovic–the 14th seed–Azarenka was able to dominate the court.

The match finished 6-1, 6-0 in favor of Azarenka.

She now goes on to face unseeded Tamira Paszek of Austria in the quarterfinals. Although Paszek is ranked 37th in the world in singles, Azarenka is not going to take her opponent lightly–she told Barry Newcombe of wimbledon.com

"It's definitely going to be a difficult match. She's been showing some amazing results, especially the match where she was down match points. It really shows a lot of toughness in her. I'm really looking forward to it. We played here last year. I'm sure this year is doing to be a different story, but I'm up for the challenge."

Even though this will most likely turn out to be a simple, convincing match for Azarenka, she is not giving herself any leeway. She is making sure that she is getting ready for this match just as if it were against Sharapova.

It would seem that Azarenka is in the right frame of mind to take a charge at the Wimbledon title this year.